"You Need to Calm Down" is a song recorded by American singer-songwriter Taylor Swift, released on June 14, 2019, as the second single from her seventh studio album, Lover. As the fourteenth track on the album, Swift wrote and produced the song with Joel Little, who also co-wrote and co-produced her previous single "Me!". "You Need to Calm Down" is an upbeat, summery synth-pop and electropop song, with a chorus of plunging echoes. It sees Swift addressing internet trolls and homophobes, voicing her support for the LGBTQ+ community. An accompanying lyric video was released on June 14, 2019. The music video was released on June 17, featuring an ensemble cast, directed by Swift and Drew Kirsch, and executive-produced by Swift and Todrick Hall.

"You Need to Calm Down" divided music critics; some praised the song for its catchiness and pro-LGBT message, while others criticized its message as confusing and cynical. The song debuted at number one in Scotland while reaching the top five in Australia, Canada, Ireland, Malaysia, New Zealand, and the United Kingdom. It debuted at the second spot on the Billboard Hot 100, becoming the second consecutive top-two single from Lover, thus tying Swift with Madonna for the most number-two hits in the chart's history; it is also Swift's record-extending sixteenth top-ten debut on the chart.

At the 2019 MTV Video Music Awards, the "You Need to Calm Down" music video received nine nominations, winning two: Video of the Year—Swift's second win in the category, following "Bad Blood", and the Video for Good. The song also received a nomination at the 62nd Grammy Awards for Best Pop Solo Performance. On August 20, 2019, a Clean Bandit remix of the song was released.